Where is intelligence located in the brain?

University of Illinois scientists have mapped the physical architecture of intelligence in the brain in one of the largest and most comprehensive analyses so far of the brain structures vital to general intelligence and to specific aspects of intellectual functioning, such as verbal comprehension and working memory.

“We found that general intelligence depends on a remarkably circumscribed neural system,” said Neuroscience professor Aron Barbey of the Decision Neuroscience Laboratory, who led the study. “Several brain regions, and the connections between them, were most important for general intelligence.

A map of intelligence in the brain

“These structures are located primarily within the left prefrontal cortex (behind the forehead), left temporal cortex (behind the ear) and left parietal cortex (at the top rear of the head) and in “white matter association tracts” that connect them.

Working with individuals with brain damage, the researchers also found that brain regions for planning, self-control and other aspects of executive function overlap to a significant extent with regions vital to general intelligence.

said brain damage often impairs multiple brain areas, complicating the task of identifying the cognitive contributions of specific brain structures.

The researchers took CT scans of the participants’ brains and administered an extensive battery of cognitive tests. They pooled the CT data to produce a collective map of the cortex, which they divided into more than 3,000 three-dimensional units called voxels.

By analyzing multiple patients with damage to a particular voxel or cluster of voxels and comparing their cognitive abilities with those of patients in whom the same structures were intact, the researchers were able to identify brain regions essential to specific cognitive functions, and those structures that contribute significantly to intelligence.

The study provides new evidence that intelligence relies not on one brain region or even the brain as a whole, Barbey said, but involves specific brain areas working together in a coordinated fashion.

“In fact, the particular regions and connections we found support an emerging body of neuroscience evidence indicating that intelligence depends on the brain’s ability to integrate information from verbal, visual, spatial and executive processes,” he said.

The findings will “open the door to further investigations into the biological basis of intelligence, exploring how the brain, genes, nutrition and the environment together interact to shape the development and continued evolution of the remarkable intellectual abilities that make us human,” Barbey said.